1. Technical Field
The disclosure relates to a conductive film in which flexibility is provided and a conductive change at a time of extension is suppressed, and to a touch panel, a display, a touch sensor, and a solar cell using the conductive film.
2. Description of the Related Art
Requiring devices or conductive materials such as sensors, displays, artificial skins for robots used in the field of electronics, particularly, various interfaces, for wearability or shape followability is increased. A flexible device which is enabled to be disposed on a curved surface, an uneven surface, or the like, and to be freely deformed is being required in accordance with a use.
As one of such a conductive material, until now, a film or glass using indium-tin oxide (ITO) is widely used as a transparent conductive material for a display. However, the ITO film has insufficient flexibility. Thus, there is a problem in that, if the ITO film is deformed, for example, bent or extended, electric resistance is largely changed, or disconnection occurs. Accordingly, as a conductive film having flexibility, a transparent conductive film formed to maintain a shape in which carbon nanotubes are highly dispersed has been researched and developed (PCT International Publication No. WO2009/057637 and Japanese Patent Unexamined Publication No. 2009-163959).
Such a conductive film using the carbon nanotube uses a plastic base such as a polyethylene terephthalate (PET) film. Thus, the conductive film has excellent bendable properties, and molding by using a mold can be performed onto an uneven surface. However, extension during molding by a mold causes resistance of a conductive layer to be increased or causes conductivity to be damaged. Thus, an increase of resistance at the time of extension is considered as a problem.
A technology (Japanese Patent Unexamined Publication No. 2014-92581) and the like in which a fine uneven shape is formed on the surface of a conductive film in order to impart anti-reflection to the conductive film are known. However, means for suppressing an increase of resistance at the time of extension in a flexible conductive film having extensibility is not reported yet.